So, you need a minimum of 120Hz for 3D? If so, then what is the point of 240Hz and higher? Is it to make the panning shots even more smoother?

As someone already mentioned it's not a real refresh rate, but a 60Hz signal interpolated to 240Hz. What you want is a TV that is 3D ready, like Panasonic's upcoming plasma series.

Any Panasonic owners that have noticed the blacks going grey on your sets? Apparently Panasonic has confirmed this issue, but are doing nothing to fix it(link).
They said that the issue's gonna be fixed in the next series though.